Photocontrol of small GTPase Ras fused with a photoresponsive protein

Abstract

Abstract The small GTPase Ras plays an important role in intracellular signal transduction and functions as a molecular switch. In this study, we used a photoresponsive protein as the molecular regulatory device to photoregulate Ras GTPase activity. Photo zipper (PZ), a variant of the photoresponsive protein Aureochrome1 developed by Hisatomi et al. was incorporated into the C-terminus of Ras as a fusion protein. The three constructs of the Ras–PZ fusion protein had spacers of different lengths between Ras and PZ. They were designed using an Escherichia coli expression system. The Ras–PZ fusion proteins exhibited photoisomerization upon blue light irradiation and in the dark. Ras–PZ dimerized upon light irradiation. Moreover, Ras GTPase activity, which is accelerated by the Ras regulators guanine nucleotide exchange factors and GTPase-activating proteins, is controlled by photoisomerization. It has been suggested that light-responsive proteins are applicable to the photoswitching of the enzymatic activity of small GTPases as photoregulatory molecular devices.